Dynamic metrology sampling with wafer uniformity control

Abstract

A method of processing a wafer is presented that includes creating a pre-processing measurement map using measured metrology data for the wafer including metrology data for at least one isolated structure on the wafer, metrology data for at least one nested structure on the wafer, bi-layer mask data, and BARC layer data. At least one pre-processing prediction map is calculated for the wafer. A pre-processing confidence map is calculated for the wafer. The pre-processing confidence map includes a set of confidence data for the plurality of dies on the wafer. A prioritized measurement site is determined when the confidence data for one or more dies is not within the confidence limits. A new measurement recipe that includes the prioritized measurement site is then created.

1 . A method of processing a wafer comprising: 
 receiving a wafer, wherein the wafer comprises a plurality of dies, each die having a patterned hard mask layer on top of at least one other layer;    determining metrology data for the wafer, wherein the metrology data includes critical dimension (CD) data for at least one hard mask feature on the wafer and data for the at least one other layer, the metrology data being determined using historical data, or measured data or a combination thereof for a first number of measurement sites on the wafer;    creating a pre-processing measurement map for the wafer using the metrology data;    calculating a first pre-processing prediction map for the wafer, the first pre-processing prediction map including a first set of predicted measured data for a first set of dies on the wafer;    calculating a second pre-processing prediction map for the wafer, the second pre-processing prediction map including a second set of predicted measured data for a second set of dies on the wafer;    calculating a pre-processing confidence map for the wafer, the pre-processing confidence map including a set of confidence data for a third set of dies on the wafer, wherein the confidence data is determined using at least the first pre-processing prediction map;    determining a prioritized measurement site when confidence data for one or more dies is not within confidence limits for the wafer; and    obtaining new metrology data for the wafer using a new measurement recipe that includes the prioritized measurement site.    
   
   
       2 . The method as claimed in  claim 1 , further comprising: 
 calculating control settings for the wafer when confidence data for substantially all of the dies is within confidence limits for the wafer; and    processing the wafer using the calculated control settings.    
   
   
       3 . The method as claimed in  claim 2 , further comprising: 
 determining a trim value using a feature size for at least one hard mask feature on the wafer; and    creating a trimmed mask layer using a Chemical Oxide Removal (COR) process.    
   
   
       4 . The method as claimed in  claim 3 , further comprising: 
 executing a chemical treatment process, wherein exposed surfaces on the wafer are chemically treated using a process gas, wherein a solid reaction product having a thickness approximately equal to the trim value is formed on at least one exposed surface; and    executing a thermal process, wherein the executing comprises evaporating the solid reaction product, thereby trimming at least one of the chemically treated exposed surfaces by approximately the trim value.    
   
   
       5 . The method as claimed in  claim 4 , further comprising: 
 etching a gate material layer using the trimmed mask layer.    
   
   
       6 . The method as claimed in  claim 5 , further comprising: 
 cleaning the etched gate material layer using an ashing process, or a wet cleaning process, or a combination thereof.    
   
   
       7 . The method as claimed in  claim 1 , wherein the patterned hard mask layer is created on top of at least one other layer using a Hard Mask Open (HMO) procedure that includes a soft mask trimming step, an ARC etching step, a BARC etching step, a hard mask etching step, or an ashing step, or a combination of two or more thereof.  
   
   
       8 . The method as claimed in  claim 1 , further comprising: 
 creating a new pre-processing measurement map using the new measured metrology data for the wafer, wherein the new pre-processing measurement map includes the prioritized measurement site;    calculating a new pre-processing prediction map for the wafer, the new pre-processing prediction map including a new set of predicted measured data for the plurality of dies on the wafer;    calculating a new confidence map for the wafer, the new confidence map including a new set of confidence data for the plurality of dies on the wafer, wherein the new confidence data is determined using the first pre-processing prediction map, the second pre-processing prediction map, or the new pre-processing prediction map, or a combination thereof;    establishing an error condition when the new confidence data for one or more dies is not within the confidence limits; and    processing the wafer when the new confidence data for substantially all of the dies is within the confidence limits.    
   
   
       9 . The method as claimed in  claim 2 , further comprising: 
 measuring the processed wafer in a metrology module when post-processing metrology data is required;    transferring the processed wafer to a holding area when post-processing metrology data is not required; and    receiving a new wafer.    
   
   
       10 . The method as claimed in  claim 9 , further comprising: 
 creating a post-processing measurement map using measured metrology data for the processed wafer including metrology data for at least one processed isolated structure on the wafer and metrology data for at least one processed nested structure on the wafer;    calculating a first post-processing prediction map for the processed wafer, the first post-processing prediction map including a first set of predicted measured data for the plurality of dies on the processed wafer;    calculating a second post-processing prediction map for the processed wafer, the second post-processing prediction map including a second set of predicted measured data for the plurality of dies on the processed wafer;    calculating a post-processing confidence map for the processed wafer, the post-processing confidence map including a set of confidence data for the plurality of dies on the processed wafer, wherein the confidence data is determined using a difference between the first post-processing prediction map and the second post-processing prediction map;    determining a second prioritized measurement site when the confidence data for one or more dies is not within the confidence limits; and    obtaining new post-processing metrology data for the wafer using a new measurement recipe that includes the second prioritized measurement site.    
   
   
       11 . The method as claimed in  claim 1 , further comprising: 
 re-measuring the processed wafer in a metrology module using the new measurement recipe when the new measurement recipe is created while the processed wafer is in the metrology module;    creating a new post-processing measurement map, wherein new measurement recipe is used to measure the processed wafer when creating the new post-processing measurement map;    calculating a new post-processing prediction map for the processed wafer, the new post-processing prediction map including a new set of predicted measured data for the plurality of dies on the processed wafer;    calculating a new confidence map for the processed wafer, the new confidence map including a new set of confidence data for the plurality of dies on the processed wafer, wherein the new confidence data is determined using the first post-processing prediction map, the second post-processing prediction map, or the new post-processing map, or a combination thereof;    establishing an error condition when the new confidence data for one or more dies is not within the confidence limits; and    removing the processed wafer from the metrology module when the new confidence data for substantially all of the dies is within the confidence limits.    
   
   
       12 . The method as claimed in  claim 1 , wherein: 
 the calculating of the first pre-processing prediction map for the wafer uses a first pre-processing equation, the first pre-processing equation being determined using measured data from two or more measurement sites located in a first direction; and    the calculating of the second pre-processing prediction map for the wafer uses a second pre-processing equation, the second pre-processing equation being determined using measured data from two or more measurement sites located in a second direction.    
   
   
       13 . The method as claimed in  claim 1 , wherein: 
 the calculating of the first pre-processing prediction map for the wafer uses a first pre-processing surface, the first pre-processing surface being determined using measured data from two or more measurement sites located in a first radial direction; and    the calculating of the second pre-processing prediction map for the wafer uses a second pre-processing surface, the second pre-processing surface being determined using measured data from two or more measurement sites located in a second radial direction.    
   
   
       14 . The method as claimed in  claim 1 , wherein: 
 the calculating of the pre-processing confidence map for the wafer uses a difference between a reference measurement map and the first pre-processing prediction map, the second pre-processing prediction map, or a averaged pre-processing prediction map.    
   
   
       15 . The method as claimed in  claim 1 , wherein: 
 the calculating of the pre-processing confidence map for the wafer uses a difference between the first pre-processing prediction map and the second pre-processing prediction map.    
   
   
       16 . The method as claimed in  claim 1 , wherein: 
 the calculating of the pre-processing confidence map for the wafer compares one or more uniformity limits to the first pre-processing prediction map, the second pre-processing prediction map, or a averaged pre-processing prediction map.    
   
   
       17 . The method as claimed in  claim 1 , wherein the determining of the prioritized measuring site includes: 
 establishing the prioritized measurement site in a first area of the wafer when one or more dies in the first are has a value in the first pre-processing prediction map, the second pre-processing prediction map, or an averaged pre-processing prediction map that exceeds one or more uniformity limits.    
   
   
       18 . The method as claimed in  claim 1 , wherein the determining of the prioritized measuring site includes: 
 establishing the prioritized measurement site in a first area of the wafer when one or more dies in the first are has a difference value that exceeds one or more uniformity limits in the first area, wherein the difference value is calculated using a difference between a reference measurement map and the first pre-processing prediction map, the second pre-processing prediction map, or a averaged pre-processing prediction map.    
   
   
       19 . The method as claimed in  claim 1 , wherein the determining of the prioritized measuring site includes: 
 establishing the prioritized measurement site in a first area of the wafer when one or more dies in the first are has a difference value that exceeds one or more uniformity limits in the first area, wherein the difference value is calculated using a difference between a uniformity limit and the first pre-processing prediction map, the second pre-processing prediction map, or a averaged pre-processing prediction map.    
   
   
       20 . The method as claimed in  claim 10 , wherein: 
 the calculating of the first post-processing prediction map for the wafer uses a first post-processing equation, the first post-processing equation being determined using measured data from two or more measurement sites located in a first direction; and    the calculating of the second post-processing prediction map for the wafer uses a second post-processing equation, the second post-processing equation being determined using measured data from two or more measurement sites located in a second direction.    
   
   
       21 . The method as claimed in  claim 10 , wherein: 
 the calculating of the first post-processing prediction map for the wafer uses a first post-processing surface, the first post-processing surface being determined using measured data from two or more measurement sites located in a first radial direction; and    the calculating of the second post-processing prediction map for the wafer using a second post-processing surface, the second post-processing surface being determined using measured data from two or more measurement sites located in a second radial direction.    
   
   
       22 . The method as claimed in  claim 10 , wherein: 
 the calculating of the post-processing confidence map for the wafer uses a difference between a reference measurement map and the first post-processing prediction map, the second post-processing prediction map, or a averaged post-processing prediction map.    
   
   
       23 . The method as claimed in  claim 10 , wherein: 
 the calculating of the post-processing confidence map for the wafer uses a difference between the first post-processing prediction map and the second post-processing prediction map.    
   
   
       24 . The method as claimed in  claim 10 , wherein: 
 the calculating of the post-processing confidence map for the wafer compares one or more uniformity limits to the first post-processing prediction map, the second post-processing prediction map, or a averaged post-processing prediction map.    
   
   
       25 . The method as claimed in  claim 10 , wherein the determining of the prioritized measuring site includes: 
 establishing the prioritized measurement site in a first area of the wafer when one or more dies in the first area has a value in the first post-processing prediction map, the second post-processing prediction map, or an averaged post-processing prediction map that exceeds one or more uniformity limits.    
   
   
       26 . The method as claimed in  claim 10 , wherein the determining of the second prioritized measurement site includes: 
 establishing the second prioritized measurement site in a first area of the wafer when one or more dies in the first area have a difference value that exceeds one or more uniformity limits in the first area, wherein the difference value is calculated using a difference between a reference measurement map and the first post-processing prediction map, the second post-processing prediction map, or a averaged post-processing prediction map.    
   
   
       27 . The method as claimed in  claim 10 , wherein the determining of the second prioritized measurement site includes: 
 establishing the second prioritized measurement site in a first area of the wafer when one or more dies in the first area has a difference value that exceeds one or more uniformity limits in the first area, wherein the difference value is calculated using a difference between a uniformity limit and the first post-processing prediction map, the second post-processing prediction map, or a averaged post-processing prediction map.